Conventionally, a target time margin for transmission of signals is identified for a given critical path within a digital integrated circuit in order to ensure correct implementations of the integrated circuit and notably of the critical path.
Generally speaking, such a monitoring device comprises one or more delay stages configured for generating an initial transmission delay (or propagation time) as a function of the target time margin. This initial delay is, for example, equal to one clock cycle of the digital integrated circuit minus the target time margin.
In order to best monitor the real time margin on the critical path, the monitoring device is therefore disposed directly on or close to the critical path.
Subsequent notably to the aging of the digital integrated circuit, the real time margin, determined by the monitoring device, tends to degrade.
Consequently, the monitoring device is also configured for warning of a partial or total violation of the target time margin, which allows the integrated circuit to carry out compensations by anticipation so as to avoid failures of the integrated circuit.
For this purpose, an adjustment of the clock frequency or of power supply voltage of the transistors within the digital integrated circuit is generally carried out.
Currently, such a monitoring device may be implemented in such a manner as to generate a fixed or programmable initial delay by using programming multiplexers.
However, the presence of these programmable multiplexers can falsify the detection of the propagation time in the monitoring device and, as a consequence, the monitoring of the critical path.